Fitzgerald knew little about profiling or linguistics when he joined the FBI in 1987. But, while assigned to the field office in New York City, he worked cases involving stalking or threatening letters sent to Jane Pauley, Bryant Gumbel, Don Imus, Donald Trump, and Rush Limbaugh, among others.

In 1995, Fitzgerald became a profiler at the FBI Academy at Quantico, Va. As part of Fitzgerald’s profiler training, he learned about analyzing communications. He later obtained a Master’s degree in linguistics from Georgetown University. (This was his second MS. His first was in Organizational Psychology at Villanova University.) As he has at his present company, The Academy Group, Fitzgerald created a linguistic-oriented database of threatening and/or suspicious letters, similar to one the Secret Service maintains.

Fitzgerald was on vacation when he was assigned to the Unabomb investigation in San Francisco. The assignment was to last 30 days. A year and a half later, he was still working the case. Eventually Fitzgerald and others persuaded the FBI Director and the Attorney General to push the New York Times and, eventually, the Washington Post to publish the document to see whether anyone recognized the author’s writing style. They got a phone call in February 1996 with a new name to add to their 2,500-long suspect list, Ted Kaczynski. The only FBI profiler who is now also a court-certified forensic linguist, Fitzgerald analyzed other writings of Kaczynski and concluded that the Unabomber probably wrote them. His findings helped narrow the investigation to Kaczynski. His 50-page probable cause affidavit, the first of its kind in federal court using text analysis, was the primary factor behind the judge signing the search warrant for Kaczynski's cabin. The rest is history.

Fitzgerald worked other high-profile cases like those of Danny Pearl, Jon Benet Ramsey, and the D.C. sniper. In that October 2002 case, using forensic linguistics along with his profiling skills, he was the first to suggest to the task force working the 10 murders that at least one suspect was an African-American. As it turned out, both convicted killers are African-American.

FBI profiler James R. Fitzgerald told the bureau in 2003 that it probably had pinpointed the wrong the man as the culprit for the anthrax mailings that killed five people, but those in charge of the investigation ignored him. Fitzgerald, analyzing the communications, offered a profile that generally excluded the initial suspect but fit the man the FBI ultimately decided was responsible for the mailings in 2001.

James R. Fitzgerald was the first person ever to provide expert testimony in US federal court in textual analysis. That was U.S. v VanWyck, 2000.

Fitzgerald now works for the Academy Group in Manassas, Va., which provides profiling services for private industry as well as a university instructor, author, and technical advisor for television programs (Criminal Minds) involving the Federal Bureau of Investigation.